Valve for fluid-pressure-actuated motors



May 28, 1929. F, JOHNSON 1,714,910

- VALVE Fon FLUID PRESSURE ACTUATED MOTORS Filed Feb. 5, 1922.

Patented May 28, 1929.

l 1,214,910 sarai raies.

, FRANK JOHNSON, or GLEN RIDGE, NEW alinear, AssIeNoa 'ro NArIoNAI. rimu- Mario COMPANY, or NEW YORK, N. Y., A coRroRATIoN or'wnsr VIRGINIA.

' VALVE FOR FLUID-RSSURE-ACTUATED MOTORS.

Application filed February 6, 1922. Serial No. 534,598.

This invention relates to valves, and particularly valves of the pneumatic type which are employed for controlling door motors of the pneumatic type.

The object of the invention is to provide a valve of the foregoing character which isl simple in structure, efficient in operation, and economical of manufacture.

A further obj ect of the invention is to proa Y riance 1s performed so rapidly and ceases so quickly that its cessation catches the valve' vide a valve of this character which will at all times be at one or the other limit of its movement, and hence is incapable of assuming at any time an intermediate position.

A further obj ect of the invention'isto provide a valve, which, due to its inherent characteristics as above set forth, will not permit the motor from becoming operative due to leakage in the pneumatic supply line blowing out of a gasket or other failure in the equipment.

Other objects of the invention will appear more fully hereinafter.

The invention consists substantially in the construction, combination, location, and relative arrangement of parts, all as will be more fully hereinafter set forth, as shown in the accompanying drawings, and finally pointed out in the appended claims.

Referring to the drawings,-

Fig. l is a view in section of a motor valve embodying my invention.

Fig. 2 is a. sectional view taken on the line 2, 2, Fig. l, looking in the -direction of the arrows.

Fig. 3 is a sectional view taken on the lin 3 3 of Fig. l. y

|The same part is designated by the same reference character wherever it occurs throughout the several views.

In the door operating art, and particularly the fluid pressure actuated motor art, employed for door operation, difficulty has heretofore been encountered, due to the valve controlling the door motor sometimes stopping at an intermediate position, so that while the door is apparently securely closed, yet the Avalve is in such a position that pressure is slowly leaking into the motor on the opening end of the motor piston, and the doorcreeps open while the train is in motion and a passenger is apt to fall through the doorway and encounters serious injury.

It has been found advisable and necessary in the electric control of doors on cars and the like, to use a form of control where a momentary touch on the opening closing button will cause the valve to move into reverse position, and so open or close the door, the valve usually employed being a balanced valve that will stay in whatever position it is placed in, and it is moved by momentarily varying the air pressure at one end orthe other, and so obtaining a difference of pressure on the piston endsof the valve. It oc casionally happens that this momentary vain an intermediate position, so that instead L of one end of the door motor being freely open to pressure and the otherend being freely open to exhaust, the tvvo ends are on the hair line of being connected to either pressure or exhaust, and the door is in an unstable and dangerous situation. n. f

It is among the special purposes of my presenty invention to providea valve which at no time can assume an intermediate position. In other words, to provide a valve which, irrespective of external conditions, will at all times maintain a position at one limit of its kmovement, for example, the position corresponding to the door closed position of the motor, except when` the valve is maintained in the other limit of its position. In general terms my invention comprises a double differential valve, and while its adaptability for use in connection with door motors of the pneumatic type has rendered the foregoing illustration thereof an important application of my invention, I wish. it to bev understood that I do not desire to be limited or restricted in this respect, as the valve ofmy invention maybe employed in connection with any instrumentality to be controlled where a non` intermediate position of the control valve is desired.

Referringto the drawings, I

have shown the valve of my invention employed in con .nection with magnet valves for controlling the exhaust of fluidpressure, and in one form of my invention I attainvthe objects of my invention as hereinabove outlined `by `theprovision of what will be apparent to be a double differential type ofmotor valve. I have shown the valve of my invention controlled by the standard type of magnet valves com' monly employed ltoday in connection with electric control of fluid pressure actuated motors for actuating doors. Referring particularly to Fig. l, reference numeral 1 designates the casting of the meter valve, which consists essentially of two cylinders 2 and 3, of relatively different diameter, in which cylinders operate pistons 4 and 5, likewise of.

slide 7 is shifted as is well understood in the f art. The connection between the pistons 4 and 5 likewise includes a relatively large piston 9 which operates in a relatively larger Y opening and when in its extreme position to the right it seats against the leather gasket 10. The piston 9 is cut away, as illustrated at 11, on its right hand face to form substantially a cup-shapedstructure, the purpose of which will be more fully hereinafter discussed. Fluid pressure is admitted to the motor valve from any suitable source throughv connection 12 provided therefor. The Huid pressure is at all times therefore in the valve motor, and has free access against the piston 5 of smaller diameter, and likewise against piston 4 of relatively larger diameter. The outer end of piston 5 is always open to atmosphere through opening 20, and the outer end of piston 4 is normally open to atmosphere through the magnet valve at that end being deenergized, so that the difference in diameter ofthe two pistons willalways hold the valve securely in the position shown, and the valve could not be reta-ined at any intermediate position. Consequently it will be seen that the structure will be in the position shown in the drawing, and normally will be retained in that position at all times. This position is the door closed position and by the term normally7 as herein used is meant said door closed position. It will readily be seen therefore that if it is desired to open the door, or, in other words, to shift the valve slide 7 by operation of the pistons 4, 5, to-

'wards the right, all that is necessary to be done is to supply fluid pressure behind the piston' 4. If pressure is supplied behind piston4, then, in that event, the assembly moves to the right. The progress of piston 5 in its cylinder 3 is unimpeded inasmuch as the cylinder is open through exhaust port 2O to the atmosphere.

I will now describethe instrumentalities employed in accordance with my invention for controlling the valve motor. In the first place, referring particularly to cylinder 3, l

vprovide an annular recess 21 provided with a perforation or'perforations 22 therein opening into the cylinder 3, as Vclearly shown.

The annular recess 21 is in communication through a passage 23 formed in the casting 1 with a port 24 controlled by a controldevice,

for example, magnet valve 25. Another port` munication with the pressurev chest of the motor valve through passage 27a in casing 1. The magnet valves 25 and'25', employed in accordance with my invention, are of identical construction, and while the valve 25 is the only one yshown with reference to ports 24 and 26, it will be understood that the same description will apply tov valve 25a with its ports 24 and 26a. In the arrangement shown magnet valve 25 consists of the usual magnet for controlling the stem'30 which operates vin the usual manner common to magnet valves, and carries thereon valves 31 and 32 adapted to seat respectively on valve seats 33 and 34. When valve 3l is on its seat 33, valve 32 is oil" of its seat 34. A spring 35 bearing against the shut off and port 24Y is in communication past valve 31 to open atmosphere through exhaust port 36. It will be understood from the foregoing explanation that valve 25;L of similar construction controls ports 24L and 26a, so that when the magnet valve is deenergized port 26EL is closed to communication,,whereas port 24a is open to exhaust. Vhen, however, magnet valve is energized port 24a is closed to exhaust and pressure fluid is allowed to flow from the pressure chest of the motor valve through connection 27, port 26a, through magnet valve to port 24a, into the portion of the cylinder 2 behind the piston 4, and thereby operate the motor inthe manner hereinbefore described. Upon this operation, as hereinbefore described, the motor moves from the position shown in Fig. 1 to its full position to the right, no pressure opposition being afforded vto the piston 5 because of the exhaust port 20. As soon as the piston 9, however,

to exhaust port 36' to open atmosphere.V TheV moment this occurs, the main or differential valve is held over to the right by the pressure of air on the large piston seal 9, so that limit of its movement even when the Huid' pressure behind the piston 4 is cut 0E. When it is desired to shift the valve motor to its other extreme position, it will be apparent that it is merely necessary to energize valve 25 to shut off the communication of port 24 to exhaust and permit pressure fluid from the central chamber to flow through passage 2T, port 26, port 24, passage 23, recess 2l, perforations 22, behind the piston 9, and thereby the pressure on its two sides as the eective area of the piston 9 is practically equal on both sides with the recess 1l provided therein. As the effective pressure area on the right side of piston 4 and cavity ll'is greater than the effective pressure area on the left side of pistons 9 and 5, it will be apparent that the valve motor will thereupon move towards the left. It will also be apparent that it is impossible to hold the motor at any intermediate point in its movement in either direction. In other words, it is absolutely necessary and essential with this structure that the elements assume their limit position in one direction or the other. By reason of the vforegoing construction it will readily be understood that the disadvantages of the present types of valve employed, particularly in door motor control work, are overcome, whereby creeping of the valve is completely eliminated with the danger incident thereto.

It will be noted that at the right hand end of the motor the piston 5 is in eflect a double piston structure. This is provided to prevent leakage of the actuating pressure should pressure be admitted to recess 21 when the valve motor is at its extreme left position.

ples thereof, what l claim as new and usefuly and of my own invention and desire to secure by Letters Patent is,

l. A fluid pressure actuated valve comprising differential cylinders, pistons operating therein, and connected together to movein unison', an auxiliary piston of larger diameter than the others and connected to move with said pistons, means for balancing the.

vpressure on vopposite sides of. saidV auxiliary piston except when at one limitof movement of said pistons, and ineansffor exhausting the pressure behind one face of said auxiliary piston when at that limit of movement of said pistons whereby said auxiliary piston is restrained at said limit. I

2. A fluid pressure actuated valve comprising differential cylinders, pist-ons operating therein, and connected together to move in unison, an auxiliary pistonof ,larger diameter than the others and connected to move ,with said pistons, means for balancin .f thev pressure on opposite sides of said auxiliary piston except when at one limit of movement of said pistons, means for exhausting the pressure behind one face of said auxiliary piston to prevent its return'when at thatlimit of movement of said pistons, and fluid pressure means for controlling the movements of said pistons. i

3. A fluid pressure actuated valve comprising differential cylinders, pistons operating therein, and connected together to move in unison, an auxiliary piston of larger diameter than the others and connected to move with said pistons, means for balancing the pressure on opposite sides of said auxiliary piston except when at one limit of movement of said pistons, means for exhausting the pressure behind one face of said auxiliary piston to prevent its return when at that limit lof movement of said pistons, and electrically controlled fluid pressure means for controlling the movements of said pistons.

4.' A fluid pressure actuated valve comprising differential cylinders, pistons operating therein, and connected together to move in unison, a device to be moved controlled by the movement of said pistons, means for normally maintaining the space behind said pistons open to exhaust, an auxiliary piston of larger diameter than the others and'connected to move with said pistons, means for balancing the pressure on opposite sides ofv said auxiliary piston except when at one limit of movement of said pistons, and means for exhausting the pressure 'behind one face yof said auxiliary piston to prevent itsreturn when at that limit of movement of said'pistons.

5. A fluid pressure actuated valve'comprising differential cylinders, pistons operating therein, and connected together to move in unison, a device to be moved controlled by the movement of said pistons, and means for normally maintaining the space behind said pisl tons open to exhaust, an auxiliary piston of larger diameter than the others and connect- -rtons open to exhaust, an auxiliary piston of f larger diameter than the others and connected to move with said pistons, means for balancing the pressure on opposite sides of said auxiliary piston except When at one limit of movement of said pistons, and means for ex hausting the pressure behind one face of said 1,5

auxiliary piston to prevent its return When at that limit of movement of said pistons, and electrically controlled fluid pressure means for controlling the movements of said pistons.

In testimony whereof I have hereunto set 20 my hand on this 19th day of January A. D., 1922. Y

FRANK JOHNSON. 

